EMERSOL® Isostearic Acids

Isostearic acid is a saturated, branched C18 fatty acid valued for its high oxidation resistance, excellent cold-temperature properties, and versatility across industrial and personal-care formulations. Its molecular structure helps provide the stability of a saturated fatty acid while limiting the close molecular packing associated with more linear alternatives.

Emery Oleochemicals manufactures EMERSOL® isostearic acids for use as additives or base stocks in fuel and lubricant applications and as emollients in personal care. Compare the available grades and explore how this chemistry can support specific formulation requirements.

Contact Us to request a sample or discuss your application with Emery’s technical team.

Isostearic Acid Quick Facts

What Is Isostearic Acid?

Isostearic acid is a branched, saturated fatty acid containing 18 carbon atoms and one carboxylic acid group. Commercial isostearic acid materials may contain a distribution of branched C18 structures rather than one universally identical isomer. PubChem provides reference information for one representative isostearic acid structure.

This chemistry combines two structural characteristics that matter to formulators:

• Branching: The branched carbon chain limits how tightly molecules can align and crystallize. This supports lower-temperature fluidity compared with more linear saturated fatty acids.
• Saturation: Low unsaturation reduces the number of oxidation-sensitive carbon-carbon double bonds. This supports oxidation, color, and odor stability over time.
• C18 chain length: The long hydrocarbon chain provides oil affinity, while the carboxylic acid group gives formulators a reactive site for salts, esters, and other derivatives.

Why Branched Fatty Acids Matter

Molecular structure influences how a fatty acid behaves during storage, processing, and end use. Linear saturated fatty acids can align closely and form ordered crystals. Branching interrupts that alignment, supporting easier liquid handling and low-temperature performance.

Branching and saturation contribute different benefits, however. Branching primarily affects molecular packing and low-temperature behavior. Saturation primarily supports oxidation resistance. Keeping that distinction clear helps formulators compare isostearic acid with both stearic acid and oleic acid.

Isostearic acid is not a universal replacement for every linear fatty acid, but it can be a strong option when low-temperature behavior and oxidation stability must work together.

Key Performance Benefits of Isostearic Acid

Cold-Temperature Performance

The branched structure helps reduce crystallization and supports fluidity at lower temperatures. Emery’s EMERSOL® 3875 and EMERSOL® 5875 each have a published titer of 10°C maximum, providing formulators with a defined starting point for evaluating handling and low-temperature performance.

Final performance will depend on the complete formulation and operating environment, so formulators should test the selected grade under representative conditions.

Oxidation, Color, and Odor Stability

EMERSOL® isostearic acids are fully saturated and have a maximum iodine value of 3. A low iodine value indicates limited unsaturation, helping explain the chemistry’s high oxidation resistance.

This can matter in lubricants, fuels, and personal-care products where degradation may affect performance, color, odor, or service life. Finished-product stability still requires application-specific testing.

Isostearic Acid in Lubricants and Fuels

Isostearic acid is used as an additive or base stock in fuel and lubricant applications. It may be used directly or reacted to create ester chemistry, depending on the required operating range and finished molecular structure.

Key formulation considerations include:

• Required operating-temperature range.
• Base-oil polarity and additive compatibility.
• Viscosity and low-temperature fluidity.
• Oxidation and thermal stability.
• Lubricity and friction-management targets.
• Metal and downstream-material compatibility.

Formulators can also explore Emery’s broader portfolio of lubricant esters and metalworking fluid additives. For additional fatty-acid chemistry, visit dimer, monomer, and isostearic acids.

Isostearic Acid in Personal Care

Isostearic acid can function as an emollient in personal-care formulations. Emollients help influence how a product spreads and feels while supporting the oil phase of the finished formula.

Its liquid behavior, low color, and oxidation resistance can be useful when balancing processing, sensory, appearance, and stability requirements. It can also serve as a building block for isostearate derivatives.

When evaluating isostearic acid for personal care, consider:

• Desired skin feel, spreadability, color, and odor.
• Compatibility with other ingredients.
• Processing temperature and manufacturing method.
• Required documentation and market-specific standards.
• Stability in the complete formulation and package.

Personal-care suitability, use level, regulatory status, and performance claims should always be confirmed for the exact grade and finished application.

Emery Isostearic Acid Product Options

Emery has more than 60 years of technical expertise in manufacturing high-quality isostearic acid. Its two EMERSOL® grades share the same published performance specifications, with the primary stated distinction involving feedstock description.

Understanding the Specifications

• Acid value measures the potassium hydroxide required to neutralize the acid in a defined sample.
• Iodine value indicates the degree of unsaturation. Lower values generally support oxidation and color stability.
• Color transmission measures material color at specified wavelengths.
• Titer describes solidification behavior and helps evaluate low-temperature handling.

Although the published ranges are the same, feedstock requirements, documentation, availability, and application-specific testing may influence grade selection. Emery’s technical team can help determine which option should advance to formulation trials.

Contact Us today to request technical data or a sample of EMERSOL® isostearic acid.

What to Consider When Choosing an Isostearic Acid Supplier

Selecting an isostearic acid supplier involves more than comparing a product name or CAS number. Formulators and purchasing teams should evaluate published specifications, feedstock requirements, quality and safety documentation, North American availability, technical support, and access to samples for pre-scale-up testing.

Emery combines more than 60 years of isostearic acid manufacturing experience with a broader portfolio of natural-based and synthetic lubricant technologies. This allows customers to evaluate the fatty acid within the context of the intended formulation rather than as an isolated raw material.

Frequently Asked Questions About Isostearic Acid

What is isostearic acid?

Isostearic acid is a saturated, branched C18 monocarboxylic acid used in fuel, lubricant, and personal-care formulations. Its branched structure supports low-temperature fluidity, while its low degree of unsaturation supports oxidation, color, and odor stability.

What is the difference between isostearic acid and stearic acid?

Both are saturated C18 fatty acids, but isostearic acid has a branched structure while stearic acid has a linear chain. Branching disrupts molecular packing, giving isostearic acid lower-temperature fluidity than linear stearic acid, which is typically a waxy solid at room temperature.

Why does branching improve cold-temperature performance?

Branches make it harder for fatty-acid molecules to align and form an ordered crystal structure. By limiting close molecular packing and crystallization, branching helps the material remain fluid at lower temperatures.

Is isostearic acid renewable?

Renewable content depends on the product and its feedstock. Emery states that EMERSOL® 3875 and EMERSOL® 5875 come from natural, renewable sources. EMERSOL® 5875 is specifically described as coming from renewable vegetable sources.

How is isostearic acid used in lubricants?

Isostearic acid may be used as an additive or base-stock component and as a starting material for ester lubricant chemistry. Its suitability depends on the base oil, reaction chemistry, concentration, operating conditions, and required lubricant performance.

How do I choose between EMERSOL® 3875 and EMERSOL® 5875?

Both products share the same published acid value, iodine value, color, and titer ranges. EMERSOL® 5875 is specifically described as coming from renewable vegetable sources. Emery should confirm availability, documentation, and application fit before selection and testing.

Contact Us and we’ll connect you with the right team for your formulation.